Troubleshooting guide for diesel fuel injection systems with Bosch inline fuel injection pumps

Tank empty or tank vent blocked

Fill tank/bleed system, check tank vent

Air in fuel system

Bleed fuel system, eliminate air leaks

Shut off/start device defective

Repair or replace

Fuel filter blocked

Replace fuel filter

Injection lines blocked/restricted

Drill to nominal I.D. or replace

Fuel supply lines blocked/restricted

Test all fuel lines -- flush or replace

Loose connections, injection lines leak or broken

Tighten the connection, eliminate the leak

Paraffin deposit in fuel filter

Replace filter, use winter fuel

Pump-to-engine timing incorrect

Readjust timing

Injection nozzle defective

Repair or replace

Engine air filter blocked

Replace air filter element

Pre-heating system defective

Test the glow plugs, replace as necessary

Injection sequence does not correspond to firing order

Install fuel injection lines in the correct order

Low idle misadjusted

Readjust idle stop screw

Maximum speed misadjusted

Readjust maximum speed screw

Overflow valve defective or blocked

Clean the orifice or replace fitting

Delivery valve leakage

Replace delivery valve (max. of 1 on 4 cyl., 2 on 6 cyl.)

Bumper spring misadjusted (RS...governors)

Readjust bumper spring

Timing device defective

Repair or replace timing device

Low or uneven engine compression

Repair as necessary

Governor misadjusted or defective

Readjust or repair

Fuel injection pump defective or cannot be adjusted

Remove pump and service

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